TweetFollow Us on Twitter

Serious Wireless

Volume Number: 19 (2003)
Issue Number: 4
Column Tag: Wireless Networking

Serious Wireless

Looking to get Point-to-Point Wireless between locations? Here's a truly robust solution.

by Neil Ticktin

Why The Change?

Some of you may recall my first wireless article a few years back (MacTech Magazine, January 2000 issue, "Going Wireless!" <http://www.mactech.com/articles/mactech/Vol.16/16.01/GoingWireless/>). In that article, I wanted to implement a reliable wireless link between my house, and the office. I specifically wanted to do anything and everything that I could to avoid the phone company for my net connection. Wireless gave me the ability to get high quality, reliable access that was completely within my control, and without any monthly fees. Sounded good to me!

And it was great. For years, I reliably had a 1.4 mbps connection between my house and my office ... a drive of about 2.5 miles, and about 1.5 miles as the bird flies. I was able to do it with off the shelf materials ... Lucent boxes (very similar technology to what's in the original Airport Base Stations, but with Lucent software to glue it all together).

The problem is, 1.4 mbps is not what it was 3+ years ago. More importantly, even though I was physically fairly close to the office, I was suffering latencies in the 30-millisecond range. Now while that's not a problem for things like web browsing, certain functions like access to our FileMaker Server were way too slow for me to use the way I wanted to.

You see, some applications move a lot of very small pieces of data around. The theory we had with our FileMaker sluggishness is that the latency was too great (especially compared to the LAN at the office), and essentially, it was causing the network to "thrash" when certain functions performed. As we saw in installing the new setup, reducing latency made a huge difference in the way these systems worked.

By the way, in case you were thinking about utilizing the new 802.11g standard at 54 mbps, beware of something. 802.11g is great for indoor LANs, but the standard is still in flux, and more importantly, the amount of distance you can get (at least inside) is about 1/3 of what is available with 802.11b. So far, I've not heard of anyone using 802.11b for outdoor point-to-point access.

The New Plan

You may remember from the previous article that I don't have line of sight from my house to the office. The solution? I knocked on the door of a neighbor up on the hill and offered him a great Internet connection in exchange for having some equipment on his roof. As you might well imagine, that's a deal that works out well for all. So, unlike many installations, I actually have a point to point-to-point connection between my house and the office. In other words, my connection goes from my house to David's house, to the office ... point to point to point.

What I needed to do now is find new equipment that could reduce the latency, as well as increase the bandwidth. I turned to my friends over at Westlink Wireless http://www.westlinkwireless.com. Eddie West helped me to take a look at the problem and recommended that we look at some of the proprietary radios out there.

The Radios

We selected the Trango Broadband radios <http://www.trangobroadband.com>. Specifically, the Access5800 Wireless Broadband Access Solution. Specifically, we're using a combination of their "Access Points" (AP) and their "Subscriber Units" (SU). The APs are typically located at the center of a network, or head-end of a wireless point of presence, and they communicate with one or more SUs. You can have up to 500 SUs per AP unit. We're using the Access Point, M5800S-AP-60, $895; and a 3 Mile Subscriber Unit, M5800S-SU, $495. (There's also a 10-mile Subscriber Unit, which has a DirecTV style dish on it.)

Radios have a certain amount of range where the signal is "visible". In Trango's terms, their AP units have a 60-degree sector. Because my house and my office are not within the same sector of visibility (they are on opposite sides of David's house), I need to have to Access Points each talking to a Subscriber Unit (4 radios in all). Put another way, the AP at my house talks to a SU at David's which is connected through a small Ethernet switch to an AP at David's which talks to an SU at my office.

The radios, and antennae are all combined into a single, weatherproof unit. No power is necessary on the roof, only at the power injector, which is likely near your router or switch. The units use a "power injector" over Ethernet. The radio can be 100 meters from the power injector. The injector has three connections -- a power cable, and two Ethernet ports (one to your LAN and one to the radio). For some installations, not having power at the radio is critical ... and it's almost always handy.


Figure 1. Access Point (the 3 mile Subscriber Unit)


Figure 2. Antenna for 10 mile Subscriber Unit Configuration

Radio Tech Stuff

These Trango radios are pretty cool. A specific benefit to us is that they are not based on one of the 802.11 standards, and are therefore they were able to do some special things, are high performance and secure. Specifically, they are based on Direct Sequence Spread Spectrum technology that operates in the ISM 5.7 - 5.8 GHz range. They theoretically deliver up to 10 Mbps user throughput reliably. An Access Point can be up to 20 miles from the SU, and supports QoS and have on the fly bandwidth throttling. Spread spectrum has the inherent advantage over other forms of transmission in that it can still recover data even in the most noisy of RF environments where other architectures fail. This isn't something new, just something very reliable and robust.

Using a proprietary protocol called SMARTPolling, the Trango radios are able to discover one another, as well deliver bandwidth more efficiently. And, if you are concerned with balancing the signal between SUs at different distances, the APs have a "power leveling" feature. As part of the "power on" sequence, the AP determines how far away a given SU is, and actively diminishes or increases its output power to ensure a quality of service.

To keep usage under control, you can optimize the Committed Information Rate / Maximum Information Rate (CIR/MIR) and provide bandwidth management/throttling per individual SU.

One of the more interesting features is the Dynamic RF Packet Sizing allows the radios to optimize data bandwidth utilization with maximum RF sensitivity. Unlike other solutions which use fixed RF packet sizes, the Access5800's protocol dynamically analyzes each Ethernet packet and transmits at an optimal length, 64 bytes (in the case of URL requests) to 1600 bytes.

SU's can be remotely managed through the AP using a host of commands or via HTTP web interface, telnet, or serial interface. The radios have a built in RSSI LED and RSSI Telnet Command for SU antenna alignment.

And, there's a fallback channel provision on the SU which offers built in redundancy. In the event an SU cannot communicate with its primary AP, the SU will intelligently search for a pre-programmed fall back AP to communicate with. This feature allows the network operator to actually sleep at night knowing that each user's network link will still be up in the morning.

But there are two features that are super cool, especially if you are familiar with installing wireless networks. First, there are internal dual polarized antennas that are software switchable -- yes, you can change the polarity through the software interface! Second, the radios have built in site survey tools that allow you to check for interference (see Listing 1).

Listing 1: Site Survey Results

ss> survey 3 v
Running site survey for 30 secs.
Press [space] then [enter] to stop
Vertical Polarization        Channel is clear if avg & max < -92dBm
freq   max    avg               freq   max    avg
Mhz    dBm    dBm    clear      Mhz    dBm    dBm    clear
5724   -87    -97     *no*      5788   -93    -99     yes 
5728   -81    -95     *no*      5792   -93    -99     yes 
5732   -80    -95     *no*      5796   -93    -99     yes 
5736   -79    -95     *no*      5800   -93    -99     yes 
5740   -79    -95     *no*      5804   -89    -99     *no*
5744   -80    -93     *no*      5808   -88    -97     *no*
5748   -82    -97     *no*      5812   -82    -97     *no*
5752   -91    -99     *no*      5816   -81    -95     *no*
5756   -93    -99     yes       5820   -80    -91     *no*
5760   -93    -99     yes       5824   -65    -80     *no*
5764   -93    -99     yes       5828   -57    -77     *no*
5768   -93    -99     yes       5832   -57    -85     *no*
5772   -93    -99     yes       5836   -57    -83     *no*
5776   -93    -99     yes       5840   -57    -83     *no*
5780   -93    -99     yes       5844   -59    -85     *no*
5784   -93    -99     yes       5848   -63    -79     *no*

Security

With all the talk about security over Wi-Fi, you may be concerned about the security offered by a wireless solution like this. I'm not. First, because these radios are proprietary, it will take a lot more effort for someone to figure them out. Second, the radios will only talk to another radio that it knows the hardware (aka MAC) address of. Third, Trango has built these radios with security in mind. I have a lot greater concerns about other attacks on our network than I do about someone entering in through this wireless entry point.

AppleTalk

If you are still using AppleTalk protocols in your network, no worries. These radios can handle them. Since AppleTalk uses AARP, you will need to turn the multicast packet switch to off (disabled). Once you do that, AppleTalk Phase 1 and 2 pass traffic with no problems. It's pretty cool to pull up a zone at my house from the office ... in fact, I have a Home Automation server at the house that stores my MP3s, and I play them in iTunes over File Sharing on a machine in my office.

Broadcasting Changes

One of the cool things about these radios is that you can have the Access Point broadcast changes to the APs. This is, obviously, especially useful if you have many SUs talking to the AP ... and again, shows the heritage of this radio being targeted for ISPs.

What's an Install Like?

These radios are intended for ISPs looking to deploy in their network. On one hand, that's great because that market won't tolerate a lot of problems ... the radios need to be robust. The flip side to this is that this is not a product that is currently being marketed to the end user. In part, that's because you should have some expertise when deploying it.

Unless you are an expert yourself, you should talk to someone who is. Our experience with Westlink Wireless showed the importance of this. Eddie's ability to size up the network environment and to work out the kinks was important to our install (mostly because we were doing point to point to point instead of point to point as most people would.) For example, I never would have known that it was better to have an AP and SU at David's instead of two AP's.

You need to make sure of several things. First, do you have radio line of sight? From my previous article, radio line of sight takes into account the shape of the zone that the radio waves travel in. This is called the "Freznel" zone. Basically, the radio waves travel between the antennas covering an area that is shaped long an elongated football. In other words, the clearance that you need halfway between the antennas is greater than right at each antenna. In many cases, this means that you are at an advantage if one of the antennae locations is at a higher elevation than the other.

You also need to make sure that you aren't trying to send the signal through or near items that could cause interference. For example, the metal flashings around the top of a chimney might be a problem if you are mounting the radio to a chimney. Or, if you were thinking that you could should the signal through foliage, some may be more tolerant than others. (I learned the hard way that pine trees are really tough to deal with and should always be avoided.)

My recommendation? Either plan for a bunch experimentation and learning, or better yet, buy the radio through a reseller like Westlink Wireless so that you have somewhere to consult if you run into issues.

The Interface

One of the things that I didn't like about the Lucent solution that I had was that it required that I talk to it through a piece of Windows software. VirtualPC, as always, came to the rescue so that I could use my Mac to configure the radios ... and VirtualPC 6 is better than ever in this way.

The Trango radios, though, can be configured not only through a web interface, but also via telnet. A quick overview of the command set gives you an idea of all that you can do with this interface.

Listing 2: Telnet interface for Trango Access Point

* ALL
? [command]                                         !
cd [..|main|net|rf|fw|ss]                           date
date <month> <day> <year>         help [command]
logout                                              opmode [ap]
reboot                                              restart
sysinfo                                             systemsetting <backup|restore>
sw [<sw #> <on|off>]                    time
time <hour> <min> <sec>
updateflash 
<mainimage|fpgaimage|sumainimage|sufpgaimage|systemsetting|sudb>

* MAIN
bcastscant <all|suid> <ch#> <h|v> [<ch#> <h|v> ...
bcastsuimage <all|suid> <regular|fast> <target hw_ver>
bcastsuimage [stop]                                 password
_password <new password> <new password>
set suid <id>                                 set apid <id>
set baseid <id>                               set ip <ip addr>
set defaultopmode [ap|su] <min,0..60>
set defaultopmode off                               set mir [on|off]
set mir threshold <kbps>
set rssitarget <threshold> <fade margin>
su <suid> [nonstop]                           su all [nonstop]
su changechannel <all|suid> <ch#> <h|v>  su [live|poweroff|priority]
su <ping|info|status> <suid>            su reboot <all|suid>
su restart <all|suid>                         su testrflink <all|suid> [r]
su powerleveling <all|suid> [target dB]
su sw <suid> <sw #> <on|off>      sudb [dload | view]
sudb add <suid> <pr|reg> <cir,kbps> <mir,kbps> <device id,hex>
sudb delete <suid>                            sudb modify <suid> <cir|mir> <kbps>
sudb modify <suid> <su2su> <group id,hex>
sudb view
* NET
ping <ip addr>                                tftpd [on|off]
* RF
cf2cf ap [default|<size>]                     freq scantable
freq channeltable                                   freq writescan [<ch#> <h|v>] ...
freq writechannel [<ch#> <freq>] ...
freq <ch #> <h|v>                       polar <h|v>
power set <dBm>                               power table
rfreport [reset]                                    rfrxthreshold <off|-80|-75|-70 |-65>
rfrxthreshold table
* FW
mainupdate                                          fpgaupdate
* SS
survey <time, sec> <h|v>                rssi <ch #> <h|v>
apsearch <secs> <ch#> <h|v> [<ch#> <h|v>]...

The Good, The Bad, and the Ugly

In general, I love these Trango products. You can't believe how useful it is to change polarity of antennae in software ... or to do a site survey from a telnet interface. More importantly, these are robust radios that are serious business, and I'm thrilled to have them in my network.

There are a couple of things that got to me on these radios, and are worthy of mention here. First, and these are minor, the RJ-45 jack on the power injector is backwards. The clip is against the wall, and it can be very difficult to pull the cord out without having a small flathead screwdriver. Also, the arm that the radio mounts on could be easier to articulate, but it's not bad.

The one thing that I truly despise in these radios is what I can best describe as an over the top security feature. Once set up, you can really only configure these units from one side of the connection because it limits where you can log in from. Remember, these things were designed for ISPs who deploy one or more APs and then have tons of SUs. The idea is that you wouldn't' want a customer to be able to telnet into a SU, so everything needs to happen from the head end side of things. Now, it is possible to log in from the SU side, but you have to do so within the first 30 or so seconds from when it's been power cycled. This is quite the pain and for me, almost useless as I want to manage things remotely, not on site. I have no problem with this feature being available as a software switch, but even if I was an ISP, I wouldn't want this feature turned on by default -- I want to be able to configure these things from both sides! And, this one sided nature doesn't stop there, you can't even ping the radio from the client side. This means that an ISP can't even ask their customer if they can ping a radio when the connection is down! What a pain for those in tech support who have chased problems only to find that the client unplugged a cable somewhere. Unfortunately, because it would take a complete rewrite to fix, I don't expect this feature to go away soon.

Another limitation is their use of "opmodes". Radios are usually configured when they are not running in either the Access Point or Subscriber Unit "opmode". Disable the opmode, and you disable the link. Enable the opmode, and you can't configure the unit. This is different from other types of radios that seem to be able to do both.

What's Coming

There are some new things coming down the pike on these radios. A new firmware upgrade will have SNMP capability (this will be a free upgrade). And, there's a dual-band version (5.3/5.8 GHz) coming soon too. Lastly, expected in May 2003, there will be a true point-to-point version of the radios, which may interest many of you.

The End Result

Proof is in the pudding, right?

These radios are fast ... I'm seeing communications at under 300 microseconds (not milliseconds) between the radios. But, a radio ping is different from an IP ping which is what we really care about.

In my point to point to point setup, I came from my older set up doing 1.4 mpbs with 30 millisecond latency to a new set up of 6-8 mbps (depends on the direction) with 5 milliseconds latency. The speed is so different and so much better that, using Retrospect Server, I'm actually now running backups of my home computers to tape drives at the office.

Doesn't get much better than that.


Neil is the publisher of MacTech Magazine. As a closet geek, he tends to experiment with some of the more interesting forms of technology, and then frightening the magazine staff by announcing he'll write about them. You can reach him at publisher@mactech.com

 

Community Search:
MacTech Search:

Software Updates via MacUpdate

Tor Browser 12.5.5 - Anonymize Web brows...
Using Tor Browser you can protect yourself against tracking, surveillance, and censorship. Tor was originally designed, implemented, and deployed as a third-generation onion-routing project of the U.... Read more
Malwarebytes 4.21.9.5141 - Adware remova...
Malwarebytes (was AdwareMedic) helps you get your Mac experience back. Malwarebytes scans for and removes code that degrades system performance or attacks your system. Making your Mac once again your... Read more
TinkerTool 9.5 - Expanded preference set...
TinkerTool is an application that gives you access to additional preference settings Apple has built into Mac OS X. This allows to activate hidden features in the operating system and in some of the... Read more
Paragon NTFS 15.11.839 - Provides full r...
Paragon NTFS breaks down the barriers between Windows and macOS. Paragon NTFS effectively solves the communication problems between the Mac system and NTFS. Write, edit, copy, move, delete files on... Read more
Apple Safari 17 - Apple's Web brows...
Apple Safari is Apple's web browser that comes bundled with the most recent macOS. Safari is faster and more energy efficient than other browsers, so sites are more responsive and your notebook... Read more
Firefox 118.0 - Fast, safe Web browser.
Firefox offers a fast, safe Web browsing experience. Browse quickly, securely, and effortlessly. With its industry-leading features, Firefox is the choice of Web development professionals and casual... Read more
ClamXAV 3.6.1 - Virus checker based on C...
ClamXAV is a popular virus checker for OS X. Time to take control ClamXAV keeps threats at bay and puts you firmly in charge of your Mac’s security. Scan a specific file or your entire hard drive.... Read more
SuperDuper! 3.8 - Advanced disk cloning/...
SuperDuper! is an advanced, yet easy to use disk copying program. It can, of course, make a straight copy, or "clone" - useful when you want to move all your data from one machine to another, or do a... Read more
Alfred 5.1.3 - Quick launcher for apps a...
Alfred is an award-winning productivity application for OS X. Alfred saves you time when you search for files online or on your Mac. Be more productive with hotkeys, keywords, and file actions at... Read more
Sketch 98.3 - Design app for UX/UI for i...
Sketch is an innovative and fresh look at vector drawing. Its intentionally minimalist design is based upon a drawing space of unlimited size and layers, free of palettes, panels, menus, windows, and... Read more

Latest Forum Discussions

See All

Listener Emails and the iPhone 15! – The...
In this week’s episode of The TouchArcade Show we finally get to a backlog of emails that have been hanging out in our inbox for, oh, about a month or so. We love getting emails as they always lead to interesting discussion about a variety of topics... | Read more »
TouchArcade Game of the Week: ‘Cypher 00...
This doesn’t happen too often, but occasionally there will be an Apple Arcade game that I adore so much I just have to pick it as the Game of the Week. Well, here we are, and Cypher 007 is one of those games. The big key point here is that Cypher... | Read more »
SwitchArcade Round-Up: ‘EA Sports FC 24’...
Hello gentle readers, and welcome to the SwitchArcade Round-Up for September 29th, 2023. In today’s article, we’ve got a ton of news to go over. Just a lot going on today, I suppose. After that, there are quite a few new releases to look at... | Read more »
‘Storyteller’ Mobile Review – Perfect fo...
I first played Daniel Benmergui’s Storyteller (Free) through its Nintendo Switch and Steam releases. Read my original review of it here. Since then, a lot of friends who played the game enjoyed it, but thought it was overpriced given the short... | Read more »
An Interview with the Legendary Yu Suzuk...
One of the cool things about my job is that every once in a while, I get to talk to the people behind the games. It’s always a pleasure. Well, today we have a really special one for you, dear friends. Mr. Yu Suzuki of Ys Net, the force behind such... | Read more »
New ‘Marvel Snap’ Update Has Balance Adj...
As we wait for the information on the new season to drop, we shall have to content ourselves with looking at the latest update to Marvel Snap (Free). It’s just a balance update, but it makes some very big changes that combined with the arrival of... | Read more »
‘Honkai Star Rail’ Version 1.4 Update Re...
At Sony’s recently-aired presentation, HoYoverse announced the Honkai Star Rail (Free) PS5 release date. Most people speculated that the next major update would arrive alongside the PS5 release. | Read more »
‘Omniheroes’ Major Update “Tide’s Cadenc...
What secrets do the depths of the sea hold? Omniheroes is revealing the mysteries of the deep with its latest “Tide’s Cadence" update, where you can look forward to scoring a free Valkyrie and limited skin among other login rewards like the 2nd... | Read more »
Recruit yourself some run-and-gun royalt...
It is always nice to see the return of a series that has lost a bit of its global staying power, and thanks to Lilith Games' latest collaboration, Warpath will be playing host the the run-and-gun legend that is Metal Slug 3. [Read more] | Read more »
‘The Elder Scrolls: Castles’ Is Availabl...
Back when Fallout Shelter (Free) released on mobile, and eventually hit consoles and PC, I didn’t think it would lead to something similar for The Elder Scrolls, but here we are. The Elder Scrolls: Castles is a new simulation game from Bethesda... | Read more »

Price Scanner via MacPrices.net

Clearance M1 Max Mac Studio available today a...
Apple has clearance M1 Max Mac Studios available in their Certified Refurbished store for $270 off original MSRP. Each Mac Studio comes with Apple’s one-year warranty, and shipping is free: – Mac... Read more
Apple continues to offer 24-inch iMacs for up...
Apple has a full range of 24-inch M1 iMacs available today in their Certified Refurbished store. Models are available starting at only $1099 and range up to $260 off original MSRP. Each iMac is in... Read more
Final weekend for Apple’s 2023 Back to School...
This is the final weekend for Apple’s Back to School Promotion 2023. It remains active until Monday, October 2nd. Education customers receive a free $150 Apple Gift Card with the purchase of a new... Read more
Apple drops prices on refurbished 13-inch M2...
Apple has dropped prices on standard-configuration 13″ M2 MacBook Pros, Certified Refurbished, to as low as $1099 and ranging up to $230 off MSRP. These are the cheapest 13″ M2 MacBook Pros for sale... Read more
14-inch M2 Max MacBook Pro on sale for $300 o...
B&H Photo has the Space Gray 14″ 30-Core GPU M2 Max MacBook Pro in stock and on sale today for $2799 including free 1-2 day shipping. Their price is $300 off Apple’s MSRP, and it’s the lowest... Read more
Apple is now selling Certified Refurbished M2...
Apple has added a full line of standard-configuration M2 Max and M2 Ultra Mac Studios available in their Certified Refurbished section starting at only $1699 and ranging up to $600 off MSRP. Each Mac... Read more
New sale: 13-inch M2 MacBook Airs starting at...
B&H Photo has 13″ MacBook Airs with M2 CPUs in stock today and on sale for $200 off Apple’s MSRP with prices available starting at only $899. Free 1-2 day delivery is available to most US... Read more
Apple has all 15-inch M2 MacBook Airs in stoc...
Apple has Certified Refurbished 15″ M2 MacBook Airs in stock today starting at only $1099 and ranging up to $230 off MSRP. These are the cheapest M2-powered 15″ MacBook Airs for sale today at Apple.... Read more
In stock: Clearance M1 Ultra Mac Studios for...
Apple has clearance M1 Ultra Mac Studios available in their Certified Refurbished store for $540 off original MSRP. Each Mac Studio comes with Apple’s one-year warranty, and shipping is free: – Mac... Read more
Back on sale: Apple’s M2 Mac minis for $100 o...
B&H Photo has Apple’s M2-powered Mac minis back in stock and on sale today for $100 off MSRP. Free 1-2 day shipping is available for most US addresses: – Mac mini M2/256GB SSD: $499, save $100 –... Read more

Jobs Board

Licensed Dental Hygienist - *Apple* River -...
Park Dental Apple River in Somerset, WI is seeking a compassionate, professional Dental Hygienist to join our team-oriented practice. COMPETITIVE PAY AND SIGN-ON Read more
Sublease Associate Optometrist- *Apple* Val...
Sublease Associate Optometrist- Apple Valley, CA- Target Optical Date: Sep 30, 2023 Brand: Target Optical Location: Apple Valley, CA, US, 92307 **Requisition Read more
*Apple* / Mac Administrator - JAMF - Amentum...
Amentum is seeking an ** Apple / Mac Administrator - JAMF** to provide support with the Apple Ecosystem to include hardware and software to join our team and Read more
Child Care Teacher - Glenda Drive/ *Apple* V...
Child Care Teacher - Glenda Drive/ Apple ValleyTeacher Share by Email Share on LinkedIn Share on Twitter Read more
Cashier - *Apple* Blossom Mall - JCPenney (...
Cashier - Apple Blossom Mall Location:Winchester, VA, United States (https://jobs.jcp.com/jobs/location/191170/winchester-va-united-states) - Apple Blossom Mall Read more
All contents are Copyright 1984-2011 by Xplain Corporation. All rights reserved. Theme designed by Icreon.